The role of stem frequency in morphological processing

In usage-based models, it is generally acknowledged that the frequency of use of a lexical item influences its representation in long term memory, its organization in lexical storage and its processing mechanism during lexical access, since repeated exposures to an item lead to its entrenchment in the minds of the speakers (e.g., Bybee 2003; Bybee and Beckner 2010; Croft and Cruse 2004; Tomasello 2003). When it comes to morphologically complex words, processing mechanisms and lexical access are crucially determined by the relative frequency of the derived word and of its morphological components (both the stem and the affix). In this paper we investigate the relationship between frequency of the stem and the frequency of the whole word by conducting a masked priming experiment on Italian. More precisely, we contrasted stems which were on average twice as frequent as the derivatives (e.g., trasferimento ‘transfer’ (112) vs. trasferire ‘to transfer’ (284); target/prime ratio: 2,53) to stems which were on average half as frequent as the derivatives (e.g., motivazione ‘motivation’ (98) vs. motivare ‘to motivate’ (44); prime/target ratio: 2,22). Results are discussed in relation with the organization of the lexical architecture, i.e., the mechanisms involved in lexical access and the criteria of organization for lexical representation.